'13 Toyota Corolla, 66,000 miles … out of the blue, when I turn on my headlights, the display lights on the radio and clock go almost completely dim. Any thoughts on this phenomenon? Thanks!
That sounds like a feature. Headlights means its nighttime, which means you need less light to see the dash and you don’t want to be blinded by the dash.
Agreed. Look for a dial that will increase the brightness of the dashboard lights when the headlights are on.
As stated above, modern cars dim the dash lights when the headlights are on. If they’re a lot dimmer than they used to be, the first thing I would check is the dimmer switch. I know from experience that it’s possible to accidentally change the setting. See page 151 of the owner’s manual (large PDF) for the location. If that’s not it, then other possible causes are a bad battery, bad battery connection, or bad alternator.
Many thanks for researching that. I just went out and checked and I think you guys must be right, it’s just funny I never noticed it before. Today was a grey rainy day so I had the headlights on and thought it odd I couldn’t see the clock or radio display at all. Now that it’s starting to get dark, they are visible, just dim. BTW, that little knob (which is also the odometer reset) only dims the instrument panel, not the clock and the radio.
On my '19 Subaru Forester there’s a dimmer to adjust the dash illumination. But it’s not controlled by the headlamp switch. There’s a sensor on the dash that dims the illumination based on the outside the car brightness. If the headlamps are on and it’s bright outside the dash stays bright.
This isn’t a new feature by any means. I remember my parents’ '84 Voyager doing the same thing when I was a kid.
Probably for European market. Here you have to have your headlights on all the time. It’s not for the driver to see better but for others to see the car.
You might want to check if the sensor is somehow blocked. That might make it overly eager to dim the dashboard in medium light when the headlights are on. That might have made the transition more obvious.